This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Vehicles, such as snowmobiles, construction vehicles, military vehicles, and agricultural vehicles, are often equipped with endless elastomeric tracks fitted over a plurality of wheels to facilitate vehicle movement. In some of these applications a vehicle drive wheel powers the vehicle track, and vehicle idler wheels function as a pulley wheel because they are not powered. In some cases the idler wheels can also be weight-bearing. Idler wheels can carry a vehicle track from the ground and up towards the drive wheel, or from the drive wheel and down towards the ground level depending on whether the idler wheels are located in the front or back ends of the vehicle.
Typically the vehicle tracks have an internal centrally positioned row of drive lugs which engage drive bars on the vehicle's drive wheel. The drive lugs, also known as guide-drive lugs, function to transmit power from the drive wheel to the track, and they also assist in retaining the track on the vehicle. Exposure to uneven terrain, environmental elements such as rain and harsh temperatures, and abrasive objects can wear on the vehicle track and in the aggregate such exposures can cause a vehicle track to misalign and erode at an undesirable rate. The edges of a misaligned track tend to rub against surrounding machinery and can unravel from the persistent friction. Such track damage can also lead to damage to the tracked vehicle.
Numerous examples of vehicle track systems are described in the prior art. U.S. Pat. No. 7,997,666 reveals a crawler traction device for a crawler vehicle, in particular a tractor, the device having a carriage, a drive sprocket rotating about a first axis, an idler wheel rotating about a second axis parallel to the first axis. The track is looped about the drive sprocket and the idler wheel and meshes with the drive sprocket along a meshing arc. The traction device has a noise and vibration damping device having an auxiliary roller which rotates about a third axis parallel to the first axis and is eccentric with respect to the drive sprocket as well as smaller in diameter than the drive sprocket. One embodiment of the vehicle track used in this system includes using tapered lateral surfaces of chain links on the vehicle track in an effort to align the vehicle track.
U.S. Pat. No. 7,552,979 discloses a track system for a ground engaging vehicle such as a tractor is provided. Track systems shown include the ability to maintain existing gear ratios and vehicle speed when interchanging wheels with track systems as described above. Embodiments shown also exhibit improved support of the track system in relation to a vehicle axle that reduces stress problems associated with the axle or related components. Another feature includes pivoting the track system in a way that prevents the track system from rotating 360° around the axle when large obstacles are encountered. One embodiment of this invention includes drive lugs with slots to provide some track alignment.
U.S. Pat. No. 9,033,431 shows a track assembly for traction of a tracked vehicle, such as an agricultural vehicle, an industrial vehicle (e.g., a construction vehicle) or a military vehicle. The track assembly comprises a plurality of wheels which comprises a drive wheel and a plurality of roller wheels, as well as an elastomeric endless track disposed around the plurality of wheels for engaging the ground. A roller wheel may comprise a wheel body and a covering on the wheel body. The covering may comprise a lateral portion dimensioned to contact a drive/guide lug of the track. The roller wheels and the track may implement a self-alignment system of the track assembly. When the roller wheels roll on the bottom run of the elastomeric endless track, the roller wheels exert opposite lateral force components on the elastomeric endless track in a widthwise direction of the elastomeric endless track which tend to align the elastomeric endless track within the track assembly.
U.S. Pat. No. 6,869,153 discloses a track assembly for moving a vehicle which includes a track having lugs including both drive and guide portions on its inner surface. The guide portions substantially abut against the track rollers of the assembly. Such abutment maintains alignment of the track between those rollers so as to prevent it from moving from side to side and interfering with feeding of the drive portions onto the assembly drive sprocket. Further, the guide portions grab against the drive sprocket to maintain contact of the drive portions therewith. Each of the above functions permits uninterrupted movement of the vehicle since the track is enabled to move in a continued path.
Attempts to prevent track misalignment by modifying drive lugs of the vehicle track using links, slots, and tapered surfaces are described in the prior art. The prior art also relies upon force components and contact between the vehicle track and the drive lugs for alignment. However, the combined teachings of the prior art do not adequately resolve track alignment problems, and for this reason there is a need for adapted idler wheels which function to align the vehicle track.